**1. Introduction**

The word cashmere in particular refers to the fine fibers of goats that are grown in high and cold regions of the world. Cashmere industry has been noticed again in textile industry in recent years. Fashion designers are passionate about animal fibers including cashmere. So there are high demands for luxury animal fibers. But demand for cashmere sometimes gets sinusoidal. Demand has increased significantly since 2011. If cashmere production's comparative advantage has been considered by producing countries, a good economic result will have been obtained.

There is not a specific cashmere-producing goat in the world, that is, there are many breeds or ecotypes that produce cashmere fibers, so in this chapter our aim from "cashmere goat" is the "cashmere-producing goats." The term of "cashmere goat" refers to goats whose main production is cashmere fibers. Biologically, there are many goats that produce cashmere fibers from their secondary follicles in the skin, but their cashmere quantities are not sufficient as we could nomenclature them as "cashmere goats".

There are some advantages of natural fibers in comparison with synthetic fibers.

Some advantages of natural fibers including animal fibers have the following particular preferences:

